Elicitors are plant immunity-triggering compounds which are currently considered as one of the most promising tools in agriculture for the induction of plant resistance to various diseases (Mejía-Teniente ... [more ▼]

Elicitors are plant immunity-triggering compounds which are currently considered as one of the most promising tools in agriculture for the induction of plant resistance to various diseases (Mejía-Teniente et al., 2010). By contributing to both economic and environmental performances of agroecosystems, they can help reducing the use of chemical inputs. Although some elicitor products are already available on the market, it appears that a variable efficiency in the field, along with an uneasy integration in the current legislation and agricultural strategies, make these tools difficult to use (Walters, Ratsep, & Havis, 2013). Besides these limitations, few elicitor treatments have yet been efficiently and specifically designed to protect crop plants such as wheat, which is grown and consumed worldwide, against major diseases threatening both their yield and quality. There is a strong need to better understand the mechanisms of induced resistance in plants and develop elicitor use in agriculture. A phD research is currently led in Gembloux Agro Bio-Tech to develop a method based on eliciting agents, tested in greenhouse and field conditions, to protect winter wheat against major diseases, namely Septoria tritici, Fusarium graminearum and Fusarium culmorum. This project focuses on the screening of a large number of elicitors from different origins and structures. In 2014, we focused the first screening experiments on the protection of wheat against Septoria tritici Blotch (STB). Two winter wheat genotypes were tested: susceptible ‘Avatar’ and semi-resistant ‘Sy Epson’. Plants at 3-leaf stage were first sprayed till runoff with different concentrations of elicitors, and then inoculated 5 days later with a Septoria tritici spore suspension (106 spores mL-1) using a hand sprayer. Control plants were treated, prior to disease inoculation, with sterile water (negative control) or with BION® (ASM, Syngenta Europe; positive control). The disease severity and incidence were scored every 2 days for 28 days post-inoculation (d.p.i) by measuring the percentage of area covered with lesions and bearing pycnidia on the third leaf. The first results of these tests should enable a first discrimination of elicitors considering their dose-efficiency to reduce disease severity. After further screening of all the elicitors in hand, a determination of the elicitation pathways of the most efficient molecules tested will be undertaken. We intend to study the influence of various factors (i.e Temperature, relative humidity, plant development stage) on the elicitation potential and develop a formulation to be finally tested under field conditions. [less ▲]

Plant growth-promoting rhizobacteria (PGPR) are one of the major biostimulant classes due to their ability to stimulate root growth, enhance mineral availability, and nutrient use efficiency in crops ... [more ▼]

Plant growth-promoting rhizobacteria (PGPR) are one of the major biostimulant classes due to their ability to stimulate root growth, enhance mineral availability, and nutrient use efficiency in crops. PGPR-containing biostimulant products could therefore make agriculture more sustainable by reducing demand for chemical fertilizer and lessen their negative environmental impacts. The aim of this project is to screen PGPR strains to (1) enhance wheat fitness level (growth, photosynthesis efficiency, stress tolerance, and yield) in combination with an optimised fertilizer level, (2) stimulate the increase in beneficial microorganism communities and suppress pathogenic ones in the wheat rhizosphere, (3) link wheat productivity to the composition of the microbial communities found in its rhizosphere, and (4) measure the impacts of such changes on soil fertility. A list of PGPR-containing biostimulants have been collected from screening, including several commercially available products (e.g. TwinN and NitroGuard, Mabiotec; Rhizocell GC, Ithec; B. subtilis FZB24 fl and Rhizo Vital 42, Abitep) as well as newly discovered PGPR strains. The biostimulants from that list have been screened in greenhouse and we expect to obtain results within next month. In parallel, several levels of nitrogen supply have been tested in combination with biostimulants to optimize agricultural practices and achieve the highest yield on field condition. A soil analysis protocols will also be built up to measure the influence of those PGPR strains on soil fertility changes and root uptake efficiency. In order to assess changes in the rhizomicrobial communities including fungi and bacteria (either pathogenic, neutral, or beneficial) under controlled or field conditions, metagenomic approaches will be set up. Finally, a maximum of three promising PGPR strains will be selected for practical agronomical application in larger field trials. [less ▲]

Wireworms, clock-beetles' larvae (Coleoptera, Elateridae), are below ground pests of many crops. They cause dramatic yield losses worldwide. Research on their ecology is crucial to undertake innovative ... [more ▼]

Wireworms, clock-beetles' larvae (Coleoptera, Elateridae), are below ground pests of many crops. They cause dramatic yield losses worldwide. Research on their ecology is crucial to undertake innovative management strategies. In the field of chemical ecology, multitrophic interactions occurring in the rhizosphere are gaining increasing attention from entomologists and agronomists. Our research aims at unveiling the role of volatile organic compounds (VOC) involved in wireworms' foraging behavior, putatively leading to host localization and/or host recognition. [less ▲]

Four predominant isolated pathogens have been identified during survey of rice diseases in three regions in Madagascar. These pathogens were the bacteria Xanthomonas oryzae pv. oryzae and Pseudomonas ... [more ▼]

Four predominant isolated pathogens have been identified during survey of rice diseases in three regions in Madagascar. These pathogens were the bacteria Xanthomonas oryzae pv. oryzae and Pseudomonas fuscovaginae and the fungi Alternaria sp. and Curvularia lunata. These pathogens are causing significant yield reduction on rice, which is the staple food in this country. After the identification of those pathogens, the objective of this work was to identify appropriate control measures against them. Plants extracts has been traditionally used to control diseases in other plant species. Nowadays, the problem of residues of phytopharmaceutical product, reinforce the need for research on the development of natural plant extracts to control plant diseases. Madagascar has many endemic plant of interest and we have evaluated the antimicrobial properties of essential oils from Malagasy plants. The main object of this study is the in-vitro screening of essential oils to control the pathogens isolated on rice in Madagascar. Thirty nine essentials oils from Madagascar had been tested. Activity of essentials oils on Pseudomonas fuscovaginae, Alternaria sp. and Curvularia lunata had been tested using broth media and on agar medium for Xanthomonas oryzae pv. oryzae. The growth of the pathogen (bacteria and conidia) in the presence of the essential oil was evaluated and compared to a control. Nine of the 39 essentials oils showed interesting antimicrobial activity with an efficiency more than 70% against at least one bacterial pathogen. One essential oil inhibited the growth of the two pathogens tested. For fungal pathogens, three essential oils presented an efficiency of more than 70% against at least one fungal pathogen. These results confirm that some essential oils present an interesting antimicrobial activity. The in-situ confirmation on plant of this activity is currently ongoing. [less ▲]

Crop plants are constantly exposed to a wide range of environmental stresses that can cause major productivity loss. Fungicide treatments are the most efficient disease control methods used up to now ... [more ▼]

Crop plants are constantly exposed to a wide range of environmental stresses that can cause major productivity loss. Fungicide treatments are the most efficient disease control methods used up to now. However, the environmental and health issues caused by these chemicals make it urgent to develop safer methods for pathogen control. In the optic of a sustainable agriculture, several biocontrol tools have been developed during the last decades. Elicitors are increasingly subject to research as interesting alternatives to phytosanitary products. Yet, few efficient formulations exist on the market, and no product has been designed specifically to protect wheat crops. This study will thus focus on the the manipulation of host natural defenses through the use of elicitors as a preventive treatment against major wheat diseases such as Septoria tritici, Fusarium graminearum and Fusarium culmorum. [less ▲]

Aquaponics is a combination of aquaculture (fish farming) and hydroponics (horticulture). In this concept, the fish faeces and excreted ammonia are partially transformed into soluble nutrients which then ... [more ▼]

Aquaponics is a combination of aquaculture (fish farming) and hydroponics (horticulture). In this concept, the fish faeces and excreted ammonia are partially transformed into soluble nutrients which then are available for plants. Wastewater from aquaculture is filtrated by plants and return to the fish tank in a loop cycle. This strongly reduces the use of water and increases the economic efficiency with an additional production of plant, e.g. vegetables. From the hydroponics view, this combination allows important decreases in chemical nutrients use for plant grow. A central part of this system is the biofilter. The microorganisms that colonize it are essential to process the fish waste into soluble nutrients easily assimilated by plants. During this process, nitrifying bacteria convert free ammonia into nitrite and then nitrate. The first objective of this research will concern the identification and isolation of the main microorganism species involved by the dilution plating and metagenomics technics. The optimal conditions to process the fish waste will be determined for such microorganism. The efficiency of nitrite and nitrate production by these micro-organisms will be tested in different conditions (T°, pH, O2, water flow, support, etc..) in vitro at the lab scale and in aquaponics prototypes. [less ▲]

The use of chemical pesticides causes problems for human health and environment. In this context, there is an increasing interest for alternative products such as biopesticides. Among them, elicitors act ... [more ▼]

The use of chemical pesticides causes problems for human health and environment. In this context, there is an increasing interest for alternative products such as biopesticides. Among them, elicitors act on the plants by inducing systemic resistance against diseases caused by fungal, viral, bacterial agents and insects. The target of the elicitors is supposed to be the plant plasma membranes (PPM). The main mechanisms of interaction of many elicitors involve proteic receptors but lipid-based elicitors (LBE) may preferably interact with the lipidic fractions of PPM. However there is no detailed information at the molecular level on the PPM-LBE interactions. Our work is focused on a original synthetic LBE composed of a mannoside linked to a myristic acid. It has potential elicitor activities as shown by the assays on tobacco root cells. These activities could be related to its interaction with the lipidic phase of PPM. Since PPM are complex entities, the analyses of the PPM- molecule interactions are quite difficult. In this context, these interactions were carried out using biomimetic membranes of PPM such as Langmuir monolayers and multilayers. The effects of our molecule on these membranar systems were investigated by biophysical and in silico approaches. [less ▲]